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排序方式: 共有80条查询结果,搜索用时 31 毫秒
31.
佛山市区酸雨时空分布特征及其成因分析 总被引:1,自引:0,他引:1
从致酸源、地理环境、工业状况、气候条件等因素分析了佛山市酸雨的成因,提出一些控制酸雨污染的建议。 相似文献
32.
N,O-bis(trimethylsily)trifluoroacetamide (BSTFA) and N-methyl-N(trimethylsily) trifluoroacetamide (MSTFA) are common derivatization reagents used in the GC-MS analysis of estrogen steroids such as estrone (E1) and 17(-ethinylestradiol (EE2). In this study, three trimethylsilyl (TMS) steroid derivatives, mono-and di-trimethylsilyl EE2 and mono-trimethylsilyl E1, were observed during the derivatization of EE2 with BSTFA or MSTFA and/or GC separation. Factors influencing the production of multiple TMS derivatives and their relative abundance were examined. It was found that both methanol and bisphenol A competed with estrogenic esteroids when reacting with silylation reagents, and thus affected the formation of TMS derivatives and their relative abundance in the derivatization products. Methanol was found to be more reactive than bisphenol A with the BSTFA reagent. None of the three solvents tested in this study could prevent the generation of multiple TMS derivatives during the derivatization of EE2 with BSTFA, followed by GC analysis. A similar result was observed using MSTFA as the derivative reagent followed by GC analysis. Thus, the suitability of BSTFA or MSTFA as the derivatization reagent for the determination of E1 and EE2 by GC-MS, under the conditions reported here, is questionable. This problem can be solved by adding trimethylsilylimidaz (TMSI) in the BSTFA reagent as recommended, and the performance of the method has been proved in this study. 相似文献
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34.
正镶白旗火山杂岩为一不规则的穹丘状地质体,它是由渐变过渡的火山碎屑岩、流纹质碎斑熔岩和次火山岩构成的一个整体.可初步划分出三个近似同心环带.中环的流纹质碎斑熔岩是火山杂岩的主体,它的众多特征反映出初始岩浆含有较多的挥发分.岩浆在地下经过了较好的结晶分异,在地下——地上某个范围内存在隐爆——侵出区.火山作用是以小规模隐爆伴随缓慢的向上侵出为主.作用时间长,形成了规模较大的火山岩.正镶白旗火山杂岩属太平洋岩系钙碱质系列,原始岩浆由来源于上地幔和下地壳熔体的混熔作用形成. 相似文献
35.
In this paper, a new in situ method for obtaining the formation factor, which is essential for the matrix diffusion, is described and tested in intrusive igneous rock. The method is based on electrical resistivity measurements in rock where the pore water and rock resistivities are essential parameters. The method is based on electromigration instead of diffusion as in traditional diffusion experiments. In previous works, quantitative formation factors of rock have been obtained by electrical methods in the laboratory. Here, a similar approach is used in situ. An in situ logging campaign was performed by SKB during 2000 in the 1700-m-deep borehole KLX02 in Laxemar, Sweden. The rock resistivity was measured with the slimhole Dual Laterolog from Antares. The groundwater resistivity was measured with the Difference Flow Meter from Posiva. A formation factor log was obtained with the maximum vertical resolution of 10 cm. In order to validate the log, 100 rock samples were taken from the bore core, and a formation factor log was obtained by using electrical methods in the laboratory. Both direct current (DC) and alternating current (AC) were used. The measurements on the core confirmed that the in situ log was quantitative, but with a possible systematic error. The in situ formation factors were on average about 1/3 to 1/5 of the laboratory formation factors, depending on depth. 相似文献
36.
Through-electromigration: a new method of investigating pore connectivity and obtaining formation factors 总被引:1,自引:0,他引:1
The retardation of radionuclides and other contaminants in fractured crystalline rock is strongly associated with the diffusive properties of the rock matrix. At present, the scientific community is divided concerning the question of long-range pore connectivity in intrusive igneous rock. This paper presents a fast new method, called the through-electromigration method, of obtaining formation factors and investigating pore connectivity. The method involves the migration of an ionic tracer through a rock sample with an electrical potential gradient as the main driving force. The method is analogous to the through-diffusion method but the experimental time is reduced by orders of magnitude. This enables investigations of pore connectivity, as measurements can be made on longer samples. In a preliminary investigation, the new method is compared to the traditional through-diffusion method as well as to rock resistivity methods. The diffusive properties of nine granitic rock samples from Laxemar in Sweden, ranging from 15 to 121 mm in length, have been investigated and the results are compared. 相似文献
37.
陕西省是我国泥石流灾害发生较严重的地区之一。本文较全面地阐明了全省泥石流灾害的时空分布规律;分析了泥石流的形成因素,并对形成泥石流的各种临界条件进行了探讨;最后,还就全省泥石流的发展趋势进行了讨论。 相似文献
38.
Sulfate aerosol contributes to particulate matter pollution and plays a key role in aerosol radiative forcing, impacting human health and climate change. Atmospheric models tend to substantially underestimate sulfate concentrations during haze episodes, indicating that there are still missing mechanisms not considered by the models. Despite recent good progress in understanding the missing sulfate sources, knowledge on different sulfate formation pathways during polluted periods still involves large uncertainties and the dominant mechanism is under heated debate, calling for more field, laboratory, and modeling work. Here, we review the traditional sulfate formation mechanisms in cloud water and also discuss the potential factors affecting multiphase S(Ⅳ) oxidation. Then recent progress in multiphase S(Ⅳ) oxidation mechanisms is summarized. Sulfate formation rates by different prevailing oxidation pathways under typical winter-haze conditions are also calculated and compared. Based on the literature reviewed, we put forward control of the atmospheric oxidation capacity as a means to abate sulfate aerosol pollution. Finally, we conclude with a concise set of research priorities for improving our understanding of sulfate formation mechanisms during polluted periods. 相似文献
39.
Disinfection is an indispensable water treatment process for killing harmful pathogens and protecting human health. However, the disinfection has caused significant public concern due to the formation of toxic disinfection by-products(DBPs). Lots of studies on disinfection and DBPs have been performed in the world since 1974. Although related studies in China started in1980 s, a great progress has been achieved during the last three decades. Therefore, this review summarized the main achievements on disinfection and DPBs studies in China, which included:(1) the occurrence of DBPs in water of China,(2) the identification and detection methods of DBPs,(3) the formation mechanisms of DBPs during disinfection process,(4) the toxicological effects and epidemiological surveys of DBPs,(5) the control and management countermeasures of DBPs in water disinfection, and(6) the challenges and chances of DBPs studies in future. It is expected that this review would provide useful information and reference for optimizing disinfection process, reducing DBPs formation and protecting human health. 相似文献
40.
根据新庄煤矿 1110 1进风巷出现不明雾气 ,笔者认为 ,研究和分析该雾气的成因及是否有毒 ,对煤矿安全生产和矿工的生命安全与健康至关重要。通过现场气象测定和实验室模拟试验 ,确定了雾气成因 ,经雾气发生地点采样分析 ,空气中未发现有毒气体。经实测分析和研究表明 ,进风巷雾气成因是 :当突然打开 1110 1工作面回风巷道中的调节风门时 ,巷道气压突然降低 ,空气膨胀 ,温度有所下降 ,使得空气中的水分凝结 ,从而形成雾气。通过实验室模拟实验再现了这一过程 ,表明对雾气现象的分析和研究的结果是正确的 相似文献